The invention relates to a device for transporting a fluid in a channel section of a microfluidic element, particularly a flow cell.
In the operation of microfluidic flow cells, as they are increasingly used for analytical and diagnostic purposes, or in syntheses as disposable products, liquids, for example, blood to be tested, must be transported within the flow cell to specific locations in order to bring the liquids into contact with, for example, reagents, or/and supply the liquids to a detection area.
A frequent task resides in separating a certain liquid quantity of liquid from a larger total sample introduced into the flow cell and to further transport the separated liquid quantity. The separated liquid quantity must frequently be further divided into partial quantities of equal or different sizes, wherein the partial quantities must be further transported. Sometimes it is also the task to bring together quantities of different liquids supplied through several channels in a single channel for the purpose of further transporting a mixture or a sequence of the quantities.
For transporting liquids within flow cells, to the trailing end of a liquid quantity in the transport direction, which in the cross-section completely fills out a channel section, pressure is applied, as this is described, for example, in U.S. Pat. Nos. 7,125,711; 6,615,856 and 6,296,020. The liquid quantity which fills out the channel section like a plug is moved because of the pressure application against the flow resistance through the channel section. The area of the channel section located in the transport direction in front of the liquid is in communication with a ventilating opening.